title: Linear and cyclic hybrids of alternating thiophene-amino acid units: synthesis and effects of chirality on conformation and molecular packing.
abstract: The dipeptide isostere 5-aminothiophene carboxylic acid has been combined with L-phenylalanine moieties to provide linear and cyclic hybrid oligopeptides. A suitable protecting group strategy and appropriate coupling methods have been developed to guarantee a high degree of enantiopurity of the resulting amides. Cyclic tetraamides have been efficiently obtained by macrocyclization of the linear derivatives. In the case of racemized cyclization precursors, two diastereomeric macrocycles (S,S/R,R and meso) have been isolated. Their crystal structures show clear effects of the stereogenic centers on the ring conformations and molecular packing.
authors.affiliation: Institut für Chemie und Biochemie, Freie Universität Berlin, Takustrasse 3, 14195 Berlin (Germany), Fax: (+49) 30-838-55367 http://www.bcp.fu-berlin.de/chemie/oc/reissig.
authors.forename: Thien H
authors.initials: TH
authors.lastname: Ngo
authors.forename: Hülya
authors.initials: H
authors.lastname: Berndt
authors.forename: Michael
authors.initials: M
authors.lastname: Wilsdorf
authors.forename: Dieter
authors.initials: D
authors.lastname: Lentz
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Reissig
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D003500:Cyclization; D004151:Dipeptides / Q000737:chemistry*; D008968:Molecular Conformation; D013876:Thiophenes / Q000737:chemistry*
chemical_list: D000596:Amino Acids; D004151:Dipeptides; D013876:Thiophenes
keywords: amino acids; crystal packing; dipeptide isosteres; macrocycles; peptidomimetics; ring conformation; thiophene